Use of 3-Isoxazolidinones as Selective Herbicides in Grass and Brassica Crops

ABSTRACT

The present invention is directed to the use of at least one 3-isoxazolidone herbicide selected from the group consisting of 2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone and 2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone as a selective herbicide in a grass or  brassica  crop selected from the group consisting of corn, rice,  sorghum , barley, rye, and canola.

This application claims the benefit of U.S. Provisional Application61/480,405, filed Apr. 29, 2011.

FIELD OF THE INVENTION

The present invention is directed to the use of at least one3-isoxazolidone herbicide selected from the group consisting of2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone and2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone as a selectiveherbicide in a grassy or brassica crop selected from the groupconsisting of corn, rice, sorghum, barley, rye, and canola/oilseed rape.

BACKGROUND OF THE INVENTION

The protection of crops from undesirable weeds which can interfere withcrop growth has long been a goal in agriculture. One approach which hasbeen taken to achieve this goal is the development of selectiveherbicides which can control weeds without exhibiting unacceptablephytotoxicity to the crops sought to be protected. More recently, cropshave been protected from weeds by genetically modifying the crop to beresistant to a non-selective herbicide (such as glyphosate orglufosinate) and applying such herbicide over the top of such crops.Unfortunately, this latter approach has led to the development ofherbicide tolerant weeds, with the result that there is still a need fora means of selectively controlling undesirable vegetation in fields.

U.S. Pat. No. 4,405,357 discloses certain 3-isoxazolidinones whichexhibit desirable selective herbicidal activity. Specifically, suchcompounds are shown to be effective in controlling grassy and broadleafspecies while leaving legumes, particularly soybeans, unaffected. Amongthe compounds specifically disclosed in this patent are2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone (Compound 22)and 2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone (Compound87). Both such compounds are demonstrated to be effective against anumber of weeds; including, for one or both of such compounds, (a)monocot grasses such green foxtail, barnyard grass, goose grass, andcrabgrass; and (b) dicot species such as chickweed, lambsquarters andvelvetleaf.

It has now been discovered that despite such desirable activity,particularly on monocot grass species, both 2,4-Cl and 2,5-Cl may beemployed as selective herbicides on grassy monocot crops including corn,rice, sorghum and sugarcane; as well as on the brassica species canola,without causing an undesirable amount of phytotoxicity to such crops.Moreover, such compounds exhibit reduced volatility relative to other3-isoxazolidinone herbicides such as clomazone.

SUMMARY OF THE INVENTION

The present invention is directed to a method of selectively controllingundesirable vegetation in a grassy monocot or brassica crop selectedfrom the group consisting of corn, rice, sorghum, sugarcane and canola(or oil seed rape) comprising applying an herbicidally effective amountof at least one 3-isoxazolidone herbicide selected from the groupconsisting of 2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidoneand 2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone to thelocus of such vegetation.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a method of selectively controllingundesirable vegetation in a grassy monocot or brassica crop selectedfrom the group consisting of corn, rice, sorghum, sugarcane and canola(or oil seed rape) comprising applying an herbicidally effective amountof at least one 3-isoxazolidone herbicide selected from the groupconsisting of 2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidoneand 2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone to thelocus of such vegetation.

As is employed herein, the term “herbicide” is used to denote a compoundwhich controls or modifies the growth of plants. The term “herbicidallyeffective amount” is used to indicate the quantity of such compoundwhich is capable of producing a controlling or modifying effect.Controlling or modifying effects include all deviations from naturaldevelopment, for example: killing, retardation, leaf burn, albinism,dwarfing, and the like. The term “plants” refers to all physical partsof a plant, including seeds, seedlings, saplings, roots, tubers, stems,stalks, foliage, and fruits.

Both 2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone(hereinafter referred to as “2,4-Cl”) and2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone (hereinafterreferred to as “2,5-Cl”) are known compounds, and may be produced byprocesses such as those described in U.S. Pat. No. 4,405,357 (Chang).

Although 2,4-Cl and 2,5-Cl may be applied pre-emergently orpost-emergently, it is preferred that they are employed pre-emergently.Such 3-isoxazolidinone compound is employed in an herbicidally effectiveamount. The amount constituting an effective amount is variable,depending on a number of factors such as the type of soil, the expectedpattern of rainfall or irrigation, the plant species to be controlled,and the particular crop involved. Typically, between about 1 and about4,000 grams of active ingredient per hectare is employed. Preferably,such compound is applied at a rate of between about 75 and 2,000 gramsa.i./hectare; and more preferably at a rate of between about 125 and1,500 grams a.i./hectare.

In the practice of the present invention, 2,4-Cl and/or 2,5-Cl aregenerally employed in the form of an agriculturally acceptableformulation comprising one or more adjuvants and/or carriers. Suchherbicidal compositions typically comprise between about 0.01% and 95%active ingredient together with between about 4% and 98.5%agriculturally acceptable carrier and between about 1% and 15% surfaceactive agent by weight. As is well-known in the art, the formulation andmode of application of a toxicant may affect the activity of thematerial in a given application. Thus, such active compounds may beformulated as an emulsifiable concentrate (EC), as a granule ofrelatively large particle size, as a wettable powder, as a solution, asa microcapsule, as a suspension concentrate (SC) or as any of severalother known types of formulations, depending on the desired mode ofapplication.

Emulsifiable concentrates are homogeneous liquid or paste compositionsdispersible in water or other dispersant, and may consist entirely of acompound of this invention with a liquid or solid emulsifying agent, ormay also contain an agriculturally acceptable liquid carrier, such asxylene, heavy aromatic naphthas, isophorone and other non-volatileorganic solvents. For example, a useful emulsifiable concentrateformulation, designated “4EC” because it contains four pounds of activeingredient per gallon of concentrate (0.479 kg/liter), contains 53 partsof 2,4-Cl and/or 2,5-Cl, 6.0 parts of a blend ofalkylnaphthalenesulfonate and polyoxyethylene ethers as emulsifiers, 1.0part of epoxidized soybean oil as stabilizer, and as solvent 40 parts ofpetroleum distillate having a high flash-point.

Granular formulations are particularly useful for aerial distribution.Useful granular formulations may be of several types. Impregnatedgranules are those wherein the active ingredient is applied to largeparticles of an absorbent carrier, such as an attapulgite or kaolinclay, corncobs, expanded mica, normally in the form of a solution in asolvent. Surface-coated granules may be produced by spraying the moltenactive ingredient onto the surface of a generally nonabsorbent particleor by spraying on a solution of active ingredient in a solvent. The coremay be water-soluble such as a prilled fertilizer, or insoluble such assand, marble chips or coarse talc. Particularly useful is a granulewherein a wettable powder is applied as a surface coating to a sand orother insoluble particle such that the wettable powder may be dispersedon contact of the granule with moisture. Granules may be produced byagglomeration of dusts or powders by compaction rollers, by extrusionthrough a die or by use of a granulating disc. Granular formulations mayvary widely in concentration, with useful formulations containing aslittle as 0.5% or as much as 95% of active ingredient.

Wettable powders, also useful formulations for preemergence herbicides,are in the form of finely divided particles which disperse readily inwater or other dispersants. The wettable powder is ultimately applied tothe soil as a finely divided dry material or as an emulsion in water orother liquid. Typical carriers for wettable powders include fuller'searth, kaolin clays, silicas and other highly absorbent, readily wetinorganic diluents. Wettable powders normally are prepared to containabout 5% to 80% of active ingredient, depending on the absorbability ofthe active ingredient and on the absorbency of the carrier, and usuallyalso contain a small amount of a wetting, dispersing or emulsifyingagent to facilitate dispersion.

2,4-Cl and 2,5-Cl may also be employed in the form of microencapsulatedformulations, such as those described in U.S. Pat. Nos. 5,597,780,5,583,090 and 5,783,520.

Typical wetting, dispersing or emulsifying agents used in agriculturalformulations include, for example, the alkyl and alkylaryl sulfonatesand sulfates and their sodium salts; polyethylene oxides; sulfonatedoils, fatty acid esters of polyhydric alcohols; and other types ofsurface active agents, many of which are available in commerce.

The surface-active agent, when used, normally comprises from 1% to 15%by weight of the herbicidal composition.

These formulations may be applied without further dilution or as dilutesolutions, emulsions or suspensions in water or other suitable diluent.The compositions may be applied to the area wherein control is desiredby spraying onto the surface of the soil in the case of liquidcompositions or by distribution from mechanical equipment in the case ofsolids. The surface-applied material may also be blended into the upperlayer of soil by cultivation, or left as applied, as is appropriate togain the optimum results with the particular treatment.

In the practice of the present invention, 2,4-Cl and/or 2,5-Cl may beformulated and/or applied with other herbicides (so long as desirableselective control of weeds is maintained), insecticides, fungicides,nematicides, plant growth regulators, fertilizers, and otheragricultural chemicals.

Example 1 EC and SC Formulations of 2,4-Cl Example 1A, EC

Into a two dram glass vial was placed 0.0227 gram of Niagara 1surfactant, 0.159 gram of Niagara 2 surfactant (Niagara surfactants areavailable from Cognis), 0.045 gram of an alkyl EO/PO copolymersurfactant (Tergitol™ XD available from Dow® Chemical), 0.463 gram of2,4-Cl and 1.3223 grams of a light aromatic solvent naphtha (Solvesso™100 Fluid available from ExxonMobil Chemical). The mixture was stirredand heated at 75° C. until all the ingredients melted. A homogenousamber liquid was obtained.

Example 1B, EC

Into a two dram glass vial was placed 0.0122 gram of Niagara 1surfactant, 0.085 gram of Niagara 2 surfactant (Niagara surfactants areavailable from Cognis), 0.0242 gram of an alkyl EO/PO copolymersurfactant (Tergitol™ XD available from Dow® Chemical), 0.69 gram of2,4-Cl and 0.705 gram of light aromatic solvent naphtha (Solvesso™ 100Fluid available from ExxonMobil Chemical). The mixture was stirred andheated at 75° C. until all the ingredients melted. A homogenous amberliquid was obtained.

Example 1C, SC

In a one liter beaker, a mixture of 46.7 grams of water, 1.5 grams of analkyl EO/PO copolymer surfactant (Tergitol™ XD available from Dow®Chemical), and 1.5 grams of an ethoxylated aliphatic alcohol phosphateester, potassium salt (Ethox ERS 129 available from Ethox Chemicals) wasstirred until all solid components had dissolved. Powdered 2,4-Cl (44.0grams) was added and the resultant slurry was transferred to an attritormill and was milled using 1 mm stainless steel balls until a particlesize of less than 12 microns (D90, Malvern light scattering particlesizer) was achieved. The mixture was filtered through a 20 mesh screento remove the milling balls. A mixture of 0.15 gram of a biocide(Proxel™ GXL Antimicrobial available from Arch® Biocides) 6.0 grams ofpropylene glycol and 0.15 gram of xanthan gum (Kelzan® M available fromCPKelco) was added to the filtrate and stirred until homogenous.

Example 2 EC Formulation of 2,5-Cl

A mixture of 45.45 grams of light aromatic solvent naphtha (Solvesso™100 Fluid available from ExxonMobil Chemical), 0.8 gram of Niagara 1surfactant, 4.91 grams of Niagara 2 surfactant (Niagara surfactants areavailable from Cognis), 1.43 grams of an alkyl EO/PO copolymersurfactant (Tergitol™ XD available from Dow® Chemical) and 47.6 grams of2,5-Cl was stirred until a homogenous solution was formed.

Example 3 Pre-Emergence Evaluation of 2,4-Cl and 2,5-Cl Formulations

The EC formulations of Examples 1 and 2 were diluted with distilledwater and were applied pre-emergently using a DeVries sprayer at ratesof 6.25, 125, 250, 375 and 500 grams of active ingredient/hectare (gai/ha) to flats containing sandy loam soil planted with crop and weedseeds, three replicates for each rate. Crop seeds used in theevaluations were grassy monocots: rice (Templeton variety), corn(Pioneer 33M53 variety), sorghum (Sorghum bicolor), rye (Loliummultiflorum), barley (Robust variety) and brassica dicot; canola/oilseedrape (Brassica napus). Weed seeds included grasses such as barnyardgrass (Echinochloa crus-galli), goose grass (Eleusine indica), crabgrass(Digitaria horizontalis) and green foxtail (Setaria viridis); andbroadleaf weeds such as field chickweed (Cerastium arvense),lambquarters (Chenopodium album) and velvetleaf (Abutilon theophrasti).Untreated control flats and two commercial formulations of Clomazone(Clomazone® 4EC Herbicide, a non-encapsulated emulsion concentrateformulation and Clomazone® 3ME Herbicide, a microencapsulatedformulation, both available from FMC Corporation) were included in eachtest. After application, the flats were placed in a greenhouse andwatered regularly. Ratings are taken at 14 days after treatment (DAT).The trials were evaluated for percent weed control and crop injury (alsolisted as % control) based on visual observations compared to theuntreated controls for each species.

Percent control was determined by a method similar to the 0 to 100rating system disclosed in “Research Methods In Weed Science,” 2nd ed.,B. Truelove, Ed.; Southern Weed Science Society; Auburn University,Auburn, Ala., 1977. The present rating system is as follows:

Rating Description Percent of main Control Categories Crop Description 0No effect No crop reduction or injury 10 Slight effect Slightdiscoloration or stunting 20 Some discoloration, stunting or stand loss30 Crop injury more pronounced but not lasting 40 Moderate effectModerate injury, crop usually recovers 50 Crop injury more lasting,recovery doubtful 60 Lasting crop injury, no recovery 70 Severe effectHeavy injury and stand loss 80 Crop nearly destroyed, a few survivors 90Only occasional plants left 100 Complete effect Complete cropdestruction

The average of the results are summarized in Table 1, Tests 1 through 5below, in which a number of crop and weed species were tested.

TABLE 1 Pre-emergence Control of Crops and Weeds 14 DAT % Control TestRate Barnyard Goose Formulation g ai/ha Rice Crabgrass Grass grass Test1 Control 0 0 0 0 4EC 250 90 100 100 100 125 58 100 86 91 62.5 18 100 6262 3ME 250 73 100 94 100 125 23 100 82 90 62.5 6 88 43 57 Example 250 55100 100 100 1A 125 17 92 82 83 62.5 5 62 65 82 Test 2 Control 0 0 0 04EC 250 82 100 100 100 125 43 100 100 98 62.5 9 100 80 70 3ME 250 55 10095 100 125 23 100 68 86 62.5 7 97 47 45 Example 250 6 97 84 53 2 125 1100 42 22 62.5 0 78 23 5 Test 3 Rate % Control Test g Lambs- Velvet-Barnyard Green Chick- Formulation ai/ha Rye Sorghum Canola quarter leafgrass foxtail weed Control 0 0 0 0 0 0 0 0 4EC 250 37 89 43 98 99 95 82100 125 28 62 31 100 90 77 60 100 62.5 8 28 0 63 63 43 23 100 3ME 250 3368 33 97 97 78 58 100 125 11 40 45 87 87 62 82 100 62.5 6 22 0 43 43 3815 100 Example 250 30 43 1 34 34 100 76 100 1B 125 15 23 0 18 18 80 42100 62.5 6 9 0 7 7 52 18 100 Example 250 17 47 0 22 22 60 28 100 2 125 823 0 18 18 35 13 100 62.5 2 7 0 3 3 20 3 90 Test 4 Rate % Control Test gBarnyard Green Formulation ai/ha Rice Corn Chickweed grass Crabgrassfoxtail Lambs-quarter Control 0 0 10 0 0 0 0 4EC 500 57 82 100 100 100100 100 375 68 85 100 100 100 100 100 250 36 39 100 100 92 100 93 125 1212 100 86 52 95 85 3ME 500 68 58 100 100 100 100 100 375 30 48 100 99 9397 100 250 17 35 100 90 62 92 96 125 6 2 100 69 20 71 72 Example 500 3227 100 100 100 100 78 1A 375 25 20 100 100 100 90 63 250 10 9 100 100100 96 40 125 0 2 100 68 70 67 28 Example 500 20 16 100 100 100 100 731C 375 23 18 100 100 100 100 62 250 10 8 100 100 100 100 43 125 1 0 10068 47 62 16 Example 500 3 9 100 84 99 92 37 2 375 0 6 100 76 68 94 20250 0 2 100 65 30 68 9 125 0 0 100 35 1 38 2 Test 5 Test Rate % ControlFormulation g ai/ha Barley Canola Control 0 0 4EC 250 25 45 125 7 5 62.521 3 3ME 250 3 19 125 0 7 62.5 0 3 Example 250 0 3 1A 125 0 0 62.5 0 0Example 250 3 0 2 125 0 0 62.5 0 0

It was found that there was significant control of weeds withoutexcessive harm to crop species.

Example 4 Volatility Evaluation

Formulations of 2,4-Cl and 2,5-Cl were tested in a greenhouse todetermine the amount of phytotoxic injury sustained by chickweed due tovolatilization of the active ingredient from treated soil. Chickweed isvery sensitive to clomazone and is a good indicator for bleachingcompound volatility. Untreated control flats and two commercialformulations of Clomazone (Command® 4EC Herbicide, a non-encapsulatedemulsion concentrate formulation and Command® 3ME Herbicide, amicroencapsulated formulation, both available from FMC Corporation) wereincluded in each test. These formulations are the reference standardsagainst which the experimental formulations are compared. Four inchplastic pots were fitted with a basket style coffee filter, cut to size,placed in the bottom of each pot to cover the drainage holes and to stopsoil from exiting the bottom of the pot. Each pot was filled with sandyloam soil that was sieved using a #10 mesh sieve to remove any largesoil particles and debris. Filled soil pots were lightly watered priorto treatment application. The test solutions were applied to the soilsurface using the DeVries Generation III sprayer, two replicates pertest solution, at a rate of 0.25 g ai/ha.

Each replicate test was set-up by placing an empty four inch plastic potonto a greenhouse bench. Pots containing mature chickweed, about 2inches in height, were placed around the empty pot in an eight spokepattern. Four pots of the mature chickweed were placed at the 3, 6, 9and 12 o'clock positions of the spoke, while three pots were placed atthe 1:30, 4:30, 7:30 and 10:30 o'clock positions of the spoke. Once allof the pots were in place, the empty four inch pot from each set-up wasremoved and a treated four inch soil pot was put in its place. Theuntreated chickweed plants were evaluated for phytotoxic injury at 14days after treatment. Volatility was evaluated by measuring the distance(cm) from the center of the treated soil pot to the distal point wherebleaching effects were observed on each spoke. All eight spokes for eachtreatment were evaluated. The amount of volatility was determined bycalculating the total square centimeters of phytotoxic injury pertreatment. Command® 4EC was considered to have zero volatility controlas this formulation consists of 100% free clomazone. The volatilityreported is relative to the Command® 4EC values which were normalized to100%. Table 2 below summarizes the average of the volatilityevaluations.

TABLE 2 Volatility Evaluations Rate of % Volatility Application Comparedto Test Formulation g ai/ha Command ® 4EC Control 0 0 Command ® 4EC 250100 Command ® 3ME 250 21.5 Example 1A 250 31.0 Example 2 250 48.8

It was found that there was significant control of volatility offormulations containing non-encapsulated 2,4-Cl and 2,5-Cl compoundswhen compared to the non-encapsulated clomazone formulation.

1-18. (canceled)
 19. A method of controlling undesirable vegetationselectively in sorghum and/or rye, the method comprising the step ofapplying to the locus of such vegetation at least one 3-isoxazolidoneherbicide selected from the group consisting of2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone and2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone in aselectively effective herbicidal amount.
 20. The method of claim 19wherein such herbicide is employed pre-emergently.
 21. The method ofclaim 20 wherein the herbicide is2-(2,4-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone.
 22. Themethod of claim 21 wherein the herbicide is employed at a rate ofbetween about 1 and about 4000 grams of active ingredient/hectare. 23.The method of claim 22 wherein the herbicide is employed at a rate ofbetween about 75 and about 2,000 grams of active ingredient/hectare. 24.The method of claim 23 wherein the herbicide is employed at a rate ofbetween about 100 and about 1,500 grams of active ingredient/hectare.25. The method of claim 20 wherein the herbicide is2-(2,5-dichlorophenyl)methyl-4,4-dimethyl-3-isoxazolidone.
 26. Themethod of claim 25 wherein the herbicide is employed at a rate ofbetween about 1 and about 4000 grams of active ingredient/hectare. 27.The method of claim 26 wherein the herbicide is employed at a rate ofbetween about 75 and about 2,000 grams of active ingredient/hectare. 28.The method of claim 27 wherein the herbicide is employed at a rate ofbetween about 100 and about 1,500 grams of active ingredient/hectare.